Island



. UNITED STATES SAMUEL MOORE. OF PROVIDENCE, RHODE ISLAND.

MANUFACTURE OF DRILLS.

SPBCIPICATICN forming part. of Letters Patent No. 315.530. dated April 14, 1885.

Application .ilril January 23, 1 3. 5.

'5 .lst-Drills, of which the following is a succification.

, Lian with its grooves had thus been brought down to the requisite thinness, the drill was.

twisted into spiral form, and the end cut oil and ground. This process has in practical use been found to be unsatisfactory and expensive. Ihc blank bcing cylindrical, it has been found almost. impracticable to start in a" I roll it down to an even thickness on each dge by the use of convczefaccd rolls, and in passing out from between the rolls't-hc blank was frequently destroyed, and always more or less injured by the rolls nipping or mashing down the end of the blank, necessitating the cutting off of quite a largo piece of [hi end of the blank after rolling. thereby wast iug the stock and enhancing the cost of manufacture. Inventive thought and skill have therefore been directed to the prevention of this waste and to the devising of means of rolling and grooving the blank so that it. will be of an even and uniform thickness. The

process of milling the drill from a. blank has hsufiicient length to form two drills and the line y y.

(X0 model.

Of course any desircdconcavity can be int nartco. the faces of the blank by the rolls, filler oh the blank is twisted into spiral form and cut into two equal parts. Thccuds are then properly ground and two drills are formed without. loss of material or sacrifice of strength in any part of the drill, and the lips are even and o uniform thickness throughout, preserving ihis uniformity while being twisted, and consequently do not require so much grinding to bring them to an oven and true finish. By using a blank long cnough to run-kc two drills as described I am enablcdto bringeach end of the blank to a finish before rolling, thereby aii'ording two true centers, by which the blank can be centered and rolle and twisted uniformly.

In the drawings, Figure l is atop plan of the blank after it has passed through the that rolls. on line 0 0. Fig. 4 is a transvcrsc section of same oulinc a :1; of Fig. 1. Fig. 5 shows theblank twisted into spiral form, and Fig. 6 shows a completed drill formed by dividing Fig. 5 centrally on A represents the body of the blank provided with shanks b b. The body A is flattened, grooved, and twisted into the spiral form, as shown, the shanks b b forming in the completed stage the shanks of the drills. After the blank is twist-ed into th form shown in Fig. 5, it is divided on the line 3 y into two equal parts, thccnds of each part. are ground and pointed, and two completed drills are produced at one operation.

I claim as new herein and .my invention and desire to secure by Letters Patent- The method described of manufacturing twist-drills, the same consisting in rolling a blank into the forms shown in Figs. 1 and 3, with a shank at; each end, and twisting such blank into the form shown in Fig. 5, dividing the same into two equal sections on the transverse line 7 1 to form two drills at each operation from a single blank, as set fort-h.

In testimony whereof I have hereunto set 21st, day of January, 1885.

SAMUEL MOORE Wit-messes: HENRY llIARSH, Jr., SULLIVAN FEXNER.

Fig. 2 is a transverse sect-ion of same Fig. 3 shows the blank grooved.

roc my hand, in presence of two witnesses, this 

